Radio frequency (RF) energy can be used to ablate solid tissue, thus inducing localized tissue necrosis. RF energy is particularly useful in this capacity, for inducing necrosis in sub-dermal lesions and tumors such as those found in cancers of the liver, stomach, kidney, lung, bowel, and pancreas. The conventional delivery system for this sort of treatment is an electro-surgical probe, and one benefit to using such a probe is that it is much less invasive than a full surgical procedure to remove the pathology.
One typical medical probe used for tumor or sub-dermal lesion ablation is comprised of a number of wire needle electrodes in an electrode array that is housed in a cannula. The electrodes in the array are extended into the diseased tissue from the distal end of the cannula, and RF energy is introduced into the tissue via the electrodes. The result is that the tissue thus treated is ablated and the tumor or lesion cells die.
Conventional probes are held using a hollow, rigid handle that is attached to the cannula at the cannula's proximal end. The handle contains wiring that connects the electrode array to an external power source, and a mechanism for extending and retracting the array.
During the surgical procedure, it is highly desirable to be able to monitor the progress of the ablation, to avoid unnecessary damage to the surrounding healthy tissue on the one hand, and insufficient ablation of the diseased tissue on the other hand. Since the ablation is occurring internally, unaided observation is not possible. Therefore, any observation must make use of such imaging techniques as ultrasound imaging, computerized axial tomography (CT) scanning, or magnetic resonance imaging (MRI).
Unfortunately, the more popular CT and MRI imaging techniques require that the patient lie inside a relatively small tubular chamber. In such close quarters there is very little maneuvering room to insert and move or adjust the probe. This problem is compounded if the patient is obese, or if the target region for the RF energy is near the surface of the body, such as when the target region is a shallow sub-dermal lesion.
Since conventional probes have rigid and relatively long handles, they are often unsatisfactory for performing an ablation surgery while simultaneously monitoring its progress using CT or MRI imaging techniques. Moreover, given the equipment that must be housed inside the handle, and the fact that the handle must fit comfortably into the surgeon's hand, it is unrealistic to attempt to solve the problem by shortening the handle enough so that it can be used inside the monitoring chamber.
Consequently, there is a significant need for a medical probe assembly that has a handle that can contain all of the necessary equipment, can comfortably fit into the surgeon's hand, and can be used within the close quarters of a CT scanner or an MRI chamber.